1. Field of the Invention
The present invention relates to an input device for shifting the position of a cursor or an icon on a display screen for a computer or the like, and an input processing method using such an input device.
2. Description of the Related Art
Conventionally, a track ball and mouse have been used as a pointing device, i.e., an input device for shifting the position of a cursor or an icon on a display screen. As shown in FIG. 91, a track ball 1 is located, for example, on a keyboard 3 of a personal computer 2. A ball 4 portion of the track ball 1 is rotated with a finger, so as to allow a cursor or an icon on a screen of the personal computer 2 to shift in a direction and by an amount determined by the direction and amount of the rotation of the ball 4.
Referring to FIG. 92, the operational principle of the track ball 1 will be briefly described. Rotary encoders 7 and 8 are disposed in two directions, X axis and Y axis, with respect to the ball 4. The encoders 7 and 8 include rollers 5 and 6, respectively, for detecting the direction and amount of rotation of the ball 4. The rotary encoders 7 and 8 generate signals indicating the direction and amount of the rotation of the ball 4. The signals are converted into electric signals corresponding to the X-axis direction and the Y-axis direction, and are transmitted to the circuitry included as part of the personal computer body. The computer body instructs the cursor or the icon on the screen to shift according to the received signals.
Each of the rotary encoders 7 and 8 includes a rotary plate 11 having a plurality of slits 10 and two sets made up of an LED 12 and a light receiving element 13 disposed to face each other with the rotary plate 11 therebetween. The rotary encoders 7 and 8 are connected to shafts 9a and 9b in the X-axis and Y-axis directions, respectively. When the ball 4 rotates in the X-axis direction, for example, the shaft 9a in the X-axis direction rotates, which rotates the rotary plate 11 of the rotary encoder 7. The rotation of the rotary plate 11 allows light emitted from the LEDs 12 to be pulsed as a result of passing through the slits 10. The pulsed signal is then converted into an electric signal by the light receiving elements 13. Thus, the rotational direction and the number of increments of rotation of the rotary plate 11 are detected, and thereby the amount of rotation of the ball 4 in the X-axis direction is determined. The position of the cursor or the icon on the screen is thus shifted in a direction on the screen corresponding to the X-axis direction by the determined amount of rotation. When the rotational direction of the ball 4 is 45.degree. with respect to the X axis and the Y axis, signals indicating the rotational direction and the same amount of rotation are obtained from both the X-axis and Y-axis rotary encoders 7 and 8 simultaneously. In such a case, the position of the cursor or the icon shifts obliquely according to the signals from the X-axis and Y-axis rotary encoders 7 and 8 as is known.
Now, referring to FIGS. 93 and 94, a mouse will be described. A mouse 15 has a ball 16, similar to the ball 4 of the track ball 1, in the lower position thereof. The mouse 15 is moved forward, backward, rightward, and leftward on an operation board 17 or on a desk, so as to shift a cursor or an icon on a computer screen. Then, a click button 18 is pressed to conduct an input operation. The inner structure of the mouse 15 is substantially the same as that of the track ball 1.
In the track ball 1, the rollers 5 and 6 which transmit the rotation of the ball 4 to the rotary encoders 7 and 8 may slip on the ball 4. This may cause malfunction of the track ball 1. Further, since it is structurally difficult to seal the rotary encoders 7 and 8, the slits 10 may be clogged with dust which has entered inside of the rotary encoders 7 and 8. This may also cause malfunction of the track ball 1. Moreover, since spaces for the track ball 1 and a mechanical operation portion for the track ball 1 are required, it is difficult to reduce the size of the personal computer.
The mouse 15 has the same problem as the track ball 1 since the mechanism for detecting the rotation of the ball 16 is the same as that of the track ball 1. Additionally, since the mouse 15 is separated from the personal computer and moved on the operation board 17 or on a desk so as to rotate the ball 16, a plane for moving the mouse 15 is required. Accordingly, the mouse is not applicable to small-size portable personal computers.
Instead of the above-described mechanical mouse 15, there is also available an optical mouse where a light emitting element and a light receiving element are provided to detect an amount of movement of the mouse in each of the X-axis and Y-axis directions. The optical mouse requires no mechanical operation portion. However, it requires a specific operation board on which the mouse is maneuvered. Therefore, the problem of the mouse requiring an additional operation space is not settled.
FIGS. 95A, 95B, and 96 show a pointing stick 20 which requires a smaller operation space than the track ball 1 and the mouse 15. The pointing stick 20 includes a rectangular parallelopiped resin rigid body 21, distortion sensors 22 attached to the four faces of the rigid body 21, and a cylindrical cover 23 covering the rigid body 21 with a space therebetween. When the cover 23 is pressed, the distortion sensors 22 detect the direction of the pressing. A cursor or an icon is shifted according to the detected direction. The pointing stick 20 with the above structure is disposed between keys 26 in a keyboard 25 of a personal computer body 24 as shown in FIG. 96. This arrangement makes it possible to significantly reduce the area and volume occupied by the pointing stick 20. However, since the pointing stick 20 is of a contact type using a contact or a distortion sensor, the reliability and the durability are low. Accordingly, a non-contact type with high reliability and durability is desirable for a frequently-used pointing device. The pointing stick 20 is also disadvantageous in the aspect of cost because the configuration for subsequent input processing is complicate.
The above conventional input devices only allow the cursor and the like to shift upward, downward, rightward, and leftward. With the recent advent of the computer graphics, it becomes necessary to also shift the cursor and the like in the depth direction of the screen. In the conventional input devices, three-dimensional screen control is not possible.
Two-dimensional input operation is possible for all of the above input devices (pointing devices). However, there requires separate switches for a click function and a drag function to realize the input operation. These switches prevent the input devices from being made smaller and more compact.